Demulsification process

Abstract

This invention relates to a process for demulsifying an emulsion which can be either of the water-in-oil or oil-in-water type, which comprises mixing the emulsion with a mixture of two or more comiscible volatile solvents, at least one of which is miscible with the water and at least one of which is miscible with the oil, thereby causing the separation of the emulsion into an oil and a water layer. Preferably, the water-miscible solvent is an alcohol and the oil-miscible solvent is a light hydrocarbon, more preferably, a saturated hydrocarbon or a monoolefin. Since it is generally desirable to recover the solvent for reuse in emulsion breaking, the oil-miscible solvent will have a boiling point of at least 50 DEG C. less than the boiling point of the oil. In the most preferred embodiment, a mixture of isopropanol and cyclohexane are mixed with an equal volume of a water-in-oil emulsion, said oil comprising high boiling hydrocarbons for a time sufficient to separate the emulsion into separate oil and water layers, said oil and water layers are then separated and distilled to recover the isopropanol and the cyclohexane.

What is claimed is: 
     
       1. In a liquid membrane process for removing a dissolved component from an aqueous feedstream which comprises contacting said feedstream with a water-inoil emulsion which is characterized as having an exterior phase which is permeable by said dissolved component, an interior phase containing a reagent which reacts with said permeable dissolved component and converts said permeable dissolved component into a non-permeable form, the improvement which comprises contacting said water-in-oil emulsion with said aqueous feedstream for a time and at conditions sufficient to convert a substantial portion of said reagent to the reaction product of said reagent and said dissolved component, separating said water-in-oil emulsion from said aqueous feedstream, demulsifying said water-in-oil emulsion by (1) mixing the emulsion, at a volume ratio of from 1/9 to 9/1, with a mixture of two or more comiscible volatile solvents, at least one of which is an alcohol or a ketone that is miscible with the water and at least one of which is a low boiling hydrocarbon or chlorinated hydrocarbon which is miscible with the oil, the weight ratio of said alcohol or ketone and hydrocarbon being from 1/9 to 9/1 and the oil miscible solvent further characterized as having a boiling point of at least 50° C less than the boiling point of the oil, under conditions of agitation, (2) terminating said agitation and allowing the mixture to separate into an oil and water layer, said water layer comprising substantially all of said reaction product and said unreacted reagent and said oil layer comprising substantially all of the components of the exterior phase of said emulsion, separating said oil and water layers, distilling off said oil miscible solvent from said oil layer, and recycling said oil back to an emulsification zone for use in preparing fresh emulsion. 
     
     
       2. The process of claim 1 further characterized by the step of separating said unreacted reagent from said water miscible solvent and recycling said unreacted reagent back to said emulsification zone for use in preparing fresh emulsion. 
     
     
       3. The process of claim 2 further characterized by recovering the reaction product of said reagent and said dissolved component, converting said reaction product to fresh reagent, and recycling said fresh reagent to said emulsification zone. 
     
     
       4. The process of claim 1 further comprising the step of distilling said water miscible solvent from said water layer, combining said distilled water miscible solvent with said distilled oil miscible solvent, and recycling said mixture to step (1) of said process. 
     
     
       5. The process of claim 1 wherein said oil miscible solvent is cyclohexane and said water miscible solvent is isopropanol. 
     
     
       6. The process of claim 1 wherein said miscible solvent is an alcohol. 
     
     
       7. The process of claim 6 wherein said alcohol is a C 1  to C 4  alcohol. 
     
     
       8. The process of claim 1 wherein said water miscible solvent is a ketone. 
     
     
       9. The process of claim 8 wherein said ketone is a C 3  to C 5  ketone.